1. Field of the Invention
The present invention relates generally to a voltage regulator, and particularly to a voltage regulator which is power saving and operable in different modes.
2. Description of Related Art
In the design of current consumer electronic products, power consumption is an important factor to be considered. For example, in handheld products, it is common to specify a limit on the power consumption of each circuit in the handheld product. For instance, when a circuit needs to operate, the power supply for that circuit is turned on, and when the circuit does not need to operate, the power supply is turned off. Therefore, a voltage regulator is required to turn on or turn off the power. However, in designing the voltage regulator, for the consideration of the circuit stability, most voltage regulator can only operate in one single mode. In addition, the maximum load current is proportional to the current consumption of the voltage regulator. Therefore, in designing the voltage regulator, the current consumption of the voltage regulator is often designed to be very large. The power consumed by this type of voltage regulator is constant no matter how much power the instantaneous load consumes. That is, when the load needs a large current, the current consumed by the voltage regulator is constant. However, as the load current becomes smaller, the current consumption of the voltage regulator still maintains constant, which appears to be unduly large when compared to the current consumption of the voltage regulator itself. Therefore, the type of voltage regulator is not power-saving.